The double amputee with drive to become racing champ
Despite losing both legs in an explosion in Afghanistan, a former soldier has set himself a new challenge - taking part in the gruelling Le Mans 24-hour motor race.
It is seven years since a roadside IED blew up next to David Birrell and changed his life completely.
"I remember everything," he told BBC Scotland's Kaye Adams programme.
The former Black Watch soldier, from Methil in Fife, says he recalls the hot blast in his face like standing behind a jet engine as a plane takes off.
There was then a big flash before his eyes and he was thrown through the air. The army interpreter who had stood on the device was killed.
"The hardest part for me, after the bomb had gone off, was confusion," he says.
"One minute I'm standing able to see everything the next I'm lying on my belly and everything is dusty and I'm wondering what had just happened," he says.
After the blast he could not feel his legs or see the extent of his injuries because of the dust.
To make matters even worse the enemy started to fire on his position as soon as the bomb went off.
David says: "When the dust went down and I saw the state of my left leg it looked fine, there wasn't a scratch on it at all but my boot was not on my foot.
"My right leg was severely injured, there was nothing on the front of it, bone was protruding through the skin.
"The rounds of fire from the enemy were landing so close that I thought I should try to get to cover behind a tree.
"So I went to get up and move and that's when I realised my left leg was badly broken. It folded underneath me."
When David was eventually taken to hospital he was surprised to learn that it was his left leg that was damaged beyond repair and required amputation.
He says: "They tried to save my right leg for about a year and a half but they came to the conclusion of amputation.
"I took me a long time to adjust to that."
The loss of his right leg led to more complications, including infections and a blood haemorrhage that almost killed him.
He says: "My heart had stopped due to blood loss and I ended up getting rushed into theatre and the next thing you know I'm waking up in a recovery room."
Looking back now he says: "What doesn't kill you makes you stronger.
"The human body is remarkable in what it can overcome."
This was the message that he tried to pass on to 17-year-old Formula 4 driver Billy Monger, who had to have both his legs amputated after a crash at Donington Park on 16 April.
David drove down to see the young racing driver at the weekend.
He says: "It was a long journey but it was worth every minute when I got there.
"It still probably won't feel real to him. I kept thinking every day I would wake up with my legs. You don't think it's real, you don't think it's forever.
"After a while it does become real - that it is forever."
He adds: "The easiest thing is to sit and dwell, the hardest thing is to get up and do something about it."
David has certainly chosen the "hard option".
He wants to be the first double-amputee to take part in the world-famous Le Mans 24-hour event, the world's oldest sports-car endurance race.
The 31-year-old has earmarked 2022 as the year he wants to reach his goal but knows he has a long way to go.
He told Kaye Adams: "I started off karting in 2012.
"I was using hand controls but I did not feel comfortable."
He was having a lot of surgery on his right stump at the time but once he was on his prosthetic legs full time he decided to try karting using them.
"I was 100 times quicker with my legs," he says.
He started to enter races against able-bodied racers at Knockhill and performed well, graduating to the MaX5 Racing Championship, which races sports cars.
'Life on the edge'
David realises there are a number of rungs to climb on the racing ladder before he can step up to Le Mans.
He is currently in the Britcar endurance race and hopes to get some international experience this year.
He will then need to race GT motors and the LMP cars used at Le Mans.
David says: "Le Mans is the world's greatest.
"It is the most gruelling race you can think of, 24 hours of man and machine. It is all about making it to the end of that race.
"It's unpredictable. It's like the army.
"You could be committed going for a corner at 100 mph and something could break and you could hit the barrier.
"It's about living life on the edge. That's when you feel most alive."
The father of three children, aged 11, nine and five, says: "There's no point in being alive if no-one is going to know who you were.
"I want to leave a mark for my kids.
"My kids are my world and all I want to do is leave a legacy for them."